Correcting device, exposure apparatus, device production method, and device produced by the device production method

ABSTRACT

A correcting device that properly maintains the flatness of a mask, an exposure apparatus in which overlay accuracy is increased by making use of the correcting device, and a device production method. The correcting device includes a gas flow path including a first area and a second area. The first area is formed above a reticle having formed thereon a pattern that is projected onto a material to be processed in order to form an image of the pattern on the material to be processed. The second area is connected to the first area, has a cross-sectional area that is different from that of the first area, and is not disposed in line with the reticle. The correcting device also includes a blowing section that blows gas to the gas flow path.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] In general, the present invention relates to an exposureapparatus. More particularly, the present invention relates to anexposure apparatus used to expose a material to be processed, such as amonocrystalline substrate for a semiconductor wafer or a glass substratefor a liquid crystal display (LCD), a correcting device that correctsdeformation of a mask or a reticle (hereafter, these terms are usedinterchangeably in the application) used in the exposure apparatus, adevice production method using the material to be processed, and adevice that is produced from the material to be processed. The presentinvention is, for example, suitable for application to an exposureapparatus which exposes a monocrystalline substrate for a semiconductorwafer by the step-and-scan projection method, the scan projectionmethod, or the step-and-repeat projection method in a photolithographyprocess.

[0003] Here, the step-and-scan projection method is a projectionexposure method in which a wafer is continuously scanned in synchronismwith a scanning movement of a mask or a reticle in order to project apattern of the mask onto the wafer by exposure, after which, aftercompletion of an exposure of one shot, the wafer is moved stepwise inorder to move the next shot to an exposure area. The scan projectionmethod is a projection exposure method in which a portion of the maskpattern is projected onto the wafer by a projection optical system andthe mask and a material to be processed are scanned in synchronism witheach other with respect to the projection optical system in order toproject the whole mask pattern onto the wafer by exposure. Thestep-and-repeat projection method is a projection exposure method inwhich the wafer is moved stepwise with each full exposure of a shot ofthe wafer in order to move the next shot to the exposure area.

[0004] 2. Description of the Related Art

[0005] In recent years, the demand for smaller and thinner electronicdevices has caused an increasing demand for finer semiconductor devicesinstalled in the electronic devices. For example, it is expected thatdesign rules of a mask pattern will become increasingly smaller in thefuture as a result of an attempt to realize a line and space (L & S) of130 nm in a mass production line. L & S refers to an image projectedonto a wafer during exposure with the widths of the lines and spacesbeing equal, so that it is a measure of exposure resolution. In theexposure, resolution, overlay accuracy, and throughput are threeimportant parameters. Resolution is defined as the smallest dimensionthat can be precisely transferred. Overlay accuracy is defined as theaccuracy with which several patterns are overlaid on a material to beprocessed. Throughput is the number of materials that are processed perunit time.

[0006] There are basically two types of exposure methods, a1×magnification transfer method and a projection method. The1×magnification transfer method includes a method in which a mask and amaterial to be processed are brought into contact with each other and amethod in which they are separated slightly. However, in the formermethod, although a high resolution can be obtained, the mask getsdamaged and the material to be processed gets scratched or defective dueto dust or pieces of silicon being pressed into the mask. In the lattermethod, the problem that exists in the former method is initiallysolved, but, when the separation between the mask and the material to beprocessed becomes smaller than the maximum size of dust particles,damage to the mask similarly occurs.

[0007] To overcome the problem that the mask and the material to beprocessed become damaged, a projection method in which the mask and thematerial to be processed are further separated has been proposed. Of thedifferent types of projection methods, the projection method that uses ascanning projection exposure apparatus is in dominant use in recentyears in order to improve resolution and to increase the size of anexposure area. In this projection method, the mask is exposed a portionat a time, and the mask and the wafer are caused to be in synchronismwith each other. By scanning the wafer either continuously orintermittently, the entire mask pattern is projected onto the wafer byexposure.

[0008] In general, a projection exposure apparatus comprises anillumination optical system that illuminates a mask and a projectionoptical system, disposed between the mask and a material to beprocessed, which projects a circuit pattern of the mask that has beenilluminated onto the material to be processed. In the illuminationoptical system, in order to obtain a uniform illumination area, lightbeams from a light source are made to enter a light integratorcomprising, for example, fly's eye lenses that are provided using aplurality of rod lenses. With a light-exiting surface of the lightintegrator being used as a secondary light source surface, these lightbeams that have entered the light integrator are used to subject a masksurface to Koehler illumination through a condenser lens.

[0009] However, when the optical axis substantially coincides with thedirection of gravitational force, the center portion of the mask isflexed by an amount on the order of a few microns in the direction ofthe gravitational force due to its own weight, resulting in a problemthat overlay accuracy is reduced during the exposure. More specifically,the following problems arise: (1) Distortion of a projected image of thepattern changes as a result of distortion of the mask pattern, and (2)focal depth, which is the focal range that allows a certainimage-formation performance to be maintained, is reduced by curvature offield. In particular, it is expected that due to the recent demand forfiner patterns, even a slight variation in the pattern must beincreasingly taken into account in the future.

[0010] To overcome such problems, Japanese Patent Laid-Open No.10-214780 proposes, in a first embodiment, to enclose a mask in order toapply static pressure to a hermetically sealed space through a pressurecontrol device. However, when the mask is enclosed, heat produced byexposure causes the mask to be distorted, so that this method is not apreferable method. In addition, the same document proposes, in a secondembodiment, to correct the distortion of the mask through apiezoelectric device disposed around the mask. However, the use of thepiezoelectric device around the mask is not necessarily effective inremoving flexure of the center portion of the mask caused by its ownweight.

[0011] Japanese Patent Laid-Open No. 6-176408 proposes to supply gashaving a predetermined pressure to a mask from a direction opposite tothe direction in which the mask flexes. However, it is difficult touniformly apply pressure to the mask. In addition, it is difficult todispose gas blowing means while maintaining an exposure optical system.

SUMMARY OF THE INVENTION

[0012] In general, it is an object of the present invention to provide anovel, useful correcting device, exposure apparatus, device productionmethod, and device produced by the production method, which make itpossible to overcome these conventional problems.

[0013] More specifically, it is an object of the present invention toprovide, for illustrative purposes, a correcting device that properlymaintains the flatness of a mask, and an exposure apparatus and a deviceproduction method, which make it possible to increase overlay accuracyby making use of the correcting device.

[0014] It is another object of the present invention to provide, as fordifferent illustrative purposes, devices, such as a high-qualitysemiconductor, a liquid crystal device (LCD), a charge-coupled device(CCD), and a thin-film magnetic head, which are produced by the deviceproduction method.

[0015] To overcome the above-described problems, according to a firstaspect, the present invention provides a correcting device comprising agas flow path including a first area and a second area, the first areabeing formed above a reticle having formed thereon a pattern that isprojected onto a material to be processed in order to form an image ofthe pattern on the material to be processed, and the second area beingconnected to the first area, having a cross-sectional area that isdifferent from that of the first area, and not being disposed in linewith the reticle; and a blowing section that blows gas to the gas flowpath.

[0016] According to this correcting device, by blowing gas (e.g., air ornitrogen) to a gas flow path having two continuously formed areas, suchas a first area and a second area, having different cross-sectionalareas, a difference in pressure between the first area and the secondarea can be produced by making use of Bernoulli's theorem. By properlymaking use of the pressure difference, the correcting device can correctdistortion caused by factors other than the self-weight of the reticle.In addition, the correcting device can restrict a rise in temperature ofthe reticle caused by exposure heat by cooling the reticle as a resultof blowing air onto it.

[0017] When a third area is provided upstream from the first area interms of the gas that is blown, and when the cross-sectional area of thethird area is greater than the cross-sectional area of the first area,it is possible to reduce the temperature of the gas in the first area,so that the rise in temperature of the reticle caused by the exposureheat can be more efficiently reduced.

[0018] When the structure of the first aspect is used, the correctingdevice may further comprise a smoothing section, disposed between thefirst and second areas, for smoothing movement of the gas between thefirst and second areas. Accordingly, the smoothing section can preventthe gas from deviating from Bernoulli's theorem caused by the gasswirling between the first and second areas. The gas flow path may beprovided opposite to the material to be processed with regard to thereticle. In general, since a pellicle film is provided at the side ofthe material to be processed, by providing the gas flow path opposite tothe material to be processed with regard to the reticle, it is possibleto prevent deformation of and damage to the pellicle film caused by airblowing across or onto the pellicle film.

[0019] When the structure of the first aspect is used, the correctingdevice may further comprise a control section that controls the blowingsection so that, when the density of the gas is ρ, the weight of thereticle is G, the area of projection of the reticle is A_(R), thecross-sectional area of the first area is A₁, the pressure of the gas inthe first area is P₁, the velocity is V₁, the cross-sectional area ofthe second area is A₂, and the pressure of the gas in the second area isP₂, the following formula is satisfied:

P ₁ −P ₂=0.5·ρ·V ₁ ²·{(A ₁ /A ₂)²−1}=−G/A _(R).

[0020] By virtue of this structure, the correcting device can correctthe distortion caused by the self-weight of the reticle. P2 may be setat atmospheric pressure. When the second area is set at atmosphericpressure and the space around the reticle is open, as disclosed in thefirst embodiment illustrated in Japanese Patent Laid-Open No. 10-214780,the exposure heat is no longer confined in the area around the recticle,so that the temperature rise of the reticle can be restricted.

[0021] According to a second aspect, the present invention provides acorrecting device comprising a blowing section that blows gas onto areticle having formed thereon a pattern to be projected onto a materialto be processed in order to form an image of the pattern on the materialto be processed; a detecting section that detects pressure at front andback surfaces of the reticle and produces a detection result; and acontrol section that controls the blowing section so that a differencebetween the pressures is maintained to be a predetermined value, afterreceiving the detection result provided by the detecting section. Thecorrecting device can correct the distortion of the reticle because thepressure difference at the front and back surfaces of the reticle iscontrolled by the control section so that it becomes a predeterminedvalue (for example, a value that cancels the deformation caused by theweight of the reticle due to gravitational force).

[0022] According to a third aspect, the present invention provides acorrecting device comprising a blowing section that blows gas onto areticle having formed thereon a pattern to be projected onto a materialto be processed in order to form an image of the pattern on the materialto be projected; a detecting section that detects a flexure amount ofthe reticle and produces a detection result; and a control section thatcontrols the blowing section so that the flexure amount is zero afterreceiving the detection result provided by the detecting section. Thecorrecting device can correct the distortion of the reticle becausefeedback is controlled by the control section so that the flexure amountof the reticle is zero.

[0023] The control sections of these correcting devices can, forexample, control the gas speed and the temperature of the gas at theblowing section.

[0024] According to a fourth aspect, the present invention provides anexposure apparatus comprising any one of the above-described correctingdevices, an illumination optical system that illuminates the pattern,and a projection optical system that projects the pattern onto thematerial to be processed in order to form an image of the pattern on thematerial to be processed. The exposure apparatus can provide theoperations of any one of the above-described correcting devices.

[0025] According to a fifth aspect, the present invention provides amethod of producing a device comprising the steps of blowing gas to agas flow path including a first area and a second area, the first areabeing formed above a reticle having formed thereon a pattern that isprojected onto a material to be processed in order to form an image ofthe pattern on the material to be processed, and the second area beingconnected to the first area, having a cross-sectional area that isdifferent from that of the first area, and not being disposed in linewith the reticle; subjecting the material to be processed to aprojection exposure operation using the reticle; and performing apredetermined processing operation on the material that has beensubjected to the projection exposure operation. The device productionmethod, which is carried out by the same operations as those of theexposure apparatus as a result of the blowing step, is used to providedevices, which are intermediate or final products. The device productionmethod may further comprise the step of detecting distortion of thereticle and the step of controlling the blowing of the gas so that thedistortion of the reticle is reduced based on a result provided by thedetection. By the control operation step, the distortion of the reticlecan be corrected with high precision. Examples of such devices aresemiconductor chips used, for example, for large-scale integration (LSI)or very large-scale integration (VLSI), charge-coupled devices (CCDs),liquid crystal devices (LCDs), magnetic sensors, and thin-film magneticheads.

[0026] Further objects, features and advantages of the present inventionwill become apparent from the following description of the preferredembodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 is a block diagram of an exposure apparatus of anembodiment of the present invention.

[0028]FIG. 2 is a schematic, sectional view used to illustrate theprinciple of a correcting device of the exposure apparatus shown in FIG.1.

[0029]FIG. 3 is a schematic, sectional view used to illustrate theprinciple of the correcting device of the exposure apparatus shown inFIG. 1.

[0030]FIG. 4 is a graph showing the relationship between upstream gaugepressure and upstream gas speed in the views shown in FIGS. 2 and 3.

[0031]FIG. 5 is a perspective view of a modification of the correctingdevice shown in FIG. 1.

[0032]FIG. 6 is a sectional view of the correcting device shown in FIG.5.

[0033]FIG. 7 is an exploded perspective view used to illustrate a methodof setting a reticle usable in the correcting device shown in FIG. 5.

[0034]FIG. 8 is a sectional view of another modification of thecorrecting device shown in FIG. 1.

[0035]FIG. 9 is a perspective view of still another modification of thecorrecting device shown in FIG. 1.

[0036]FIG. 10 is a sectional view of the correcting device shown in FIG.9.

[0037]FIG. 11 is a perspective view of still another modification of thecorrecting device shown in FIG. 1.

[0038]FIG. 12 is a sectional view of still another modification of theexposure apparatus and of the correcting device shown in FIG. 1.

[0039]FIG. 13 is a sectional view showing a state in which the reticlehas moved in the sectional view of FIG. 12.

[0040]FIG. 14 is a schematic, side view of the exposure apparatus shownin FIGS. 12 and 13.

[0041]FIG. 15 is an external perspective view of the exposure apparatusshown in FIG. 14.

[0042]FIG. 16 is a schematic block diagram of a detecting section thatdetects distortion of the reticle used in the exposure apparatus shownin FIG. 1.

[0043]FIG. 17 is a flowchart used to illustrate a device productionmethod including an exposure step in accordance with the presentinvention.

[0044]FIG. 18 is a detailed flowchart of Step 4 shown in FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Hereafter, for illustrative purposes, an exposure apparatus 1 ofthe present invention will be described with reference to the attacheddrawings. FIG. 1 shows an optical path of a simplified optical system ofthe illustrative exposure apparatus 1 of the present invention.

[0046] As shown in FIG. 1, the exposure apparatus 1 comprises anillumination device 10, a reticle 20, a projection optical system 30, aplate 40, and a correcting device 100. The exposure apparatus 1 is ascanning projection exposure apparatus which, by exposure, projects acircuit pattern formed on the reticle 20 onto the plate 40 by thestep-and-repeat projection exposure method or the step-and-scanprojection exposure method.

[0047] The illumination device 10 illuminates the reticle 20 on whichthe circuit pattern to be transferred is formed, and comprises a lightsource 12 and an illumination optical system 14.

[0048] For the light source 12, a laser may be used. For the laser, anArF excimer laser having a wavelength of approximately 193 nm, a KrFexcimer laser having a wavelength of approximately 248 nm, or an F₂excimer laser having a wavelength of approximately 153 nm may be used.However, the types of lasers which may be used are not limited toexcimer lasers, so that, for example, a yttrium-aluminum-garnet (YAG)laser may be used. The number of lasers used is not limited. When alaser is used as the light source 12, it is preferable to use alight-beam shaping optical system that shapes parallel light beams fromthe laser light source into beams having desired forms and an opticalsystem that converts coherent laser light beams into incoherent lightbeams. The types of light sources that can be used as the light source12 are not limited to lasers, so that one or a plurality of mercurylamps, xenon lamps, etc., may be used.

[0049] The illumination optical system 14 illuminates the mask 20, andincludes a lens, a mirror, a light integrator, and a stop. For example,a condenser lens, a fly's eye lens, an aperture stop, a condenser lens,a slit, and an image-forming optical system are disposed in that order.The illumination optical system 14 is used regardless of whether thelight is axial or oblique light. Examples of the light integratorinclude integrators formed by placing fly's eye lenses or two sets ofcylindrical lens array (or reticular lens) plates upon each other. Thelight integrator may be replaced by an optical rod or a diffractingdevice.

[0050] A circuit pattern (or image) to be transferred is formed on thereticle 20. Diffraction light coming from the reticle 20 is projectedonto the plate 40 through the projection optical system 30. The plate 40is a material to be processed, such as a wafer or a liquid crystalsubstrate, and has a resist coated thereto. The reticle 20 and the plate40 are in a conjugate relationship. In the embodiment, an optical axisOO′ shown in FIG. 1 matches the direction of gravitational force. Thereticle 20 used in the embodiment is formed of quartz and has a densityof approximately 2200 kg/m³, a size of 152 mm in the vertical direction× a size of 152 mm in the horizontal direction × a size of 6.35 mm inthe height direction, and a weight of 323 gf (=3.17 N), which isapproximately equivalent to a pressure of 140 Pa.

[0051] When a scanning projection exposure apparatus is used, thepattern on the mask 20 is transferred onto the plate 40 by scanning themask 20 and the plate 40 in synchronism with each other. When a stepper(or an exposure apparatus using the step-and-repeat exposure method) isused, exposure is performed while the mask 20 and the plate 40 arestopped.

[0052] For the projection optical system 30, there may be used, forexample, an optical system comprising only a plurality of lens elements,an optical system (catadioptric optical system) including a plurality oflens elements and at least one concave mirror, an optical systemincluding a plurality of lens elements and at least one diffractingoptical element such as a saw-tooth shaped diffracting optical element,or an optical system which is entirely a mirror may be used. Whenchromatic aberration needs to be corrected, the projection opticalsystem 30 may be formed using a plurality of lens elements formed ofglass materials having different variances (Abbe numbers) or thediffracting optical element may be formed so that scattering occurs in adirection opposite to the lens elements.

[0053] The plate 40 is coated with a photoresist. The photoresistapplying step consists of a pre-processing operation, an operation forapplying an adhesiveness increasing agent, a photoresist applyingoperation, and a pre-baking operation. The pre-processing operationincludes cleaning, drying, and the like. The operation for applying anadhesiveness increasing agent is carried out to modify the surface ofthe plate 40 (that is, to increase its hydrophobic property by applyinga surface active agent), so that the adhesiveness between thephotoresist and a base is increased. In the operation for applying anadhesiveness increasing agent, an organic film, such as ahexamethyl-disilazane (HMDS) film, is applied or evaporated. Thepre-baking operation is a baking operation, but provides a softersurface than that after development, and is carried out to removesolvent.

[0054] The correcting device 100 corrects distortion or flexure of thereticle 20. The reticle 20 is flexed due to its own weight by a fewmicrons in the direction of a gravitational force that is parallel tothe optical axis OO′ shown in FIG. 1. Therefore, the correcting device100 first corrects the distortion of the reticle 20 caused by its ownweight by making use of Bernoulli's theorem. The correcting device 100comprises a gas pipe 110, which forms a gas flow path 111, and a blowingsection 120, which blows gas to the gas flow path 111. The gas flow path111 comprises an area 112, which is situated above or below the reticle20, and an area 114, which is not situated in line with the reticle 20.

[0055] The principle of the correcting device 100 will be described withreference to FIGS. 2 and 3. Here, FIGS. 2 and 3 are schematic, sectionalviews used to illustrate the principle of the correcting device 100.FIG. 2 illustrates the case in which a gas flow path 111A is disposedbelow the reticle 20, and FIG. 3 illustrates the case in which a gasflow path 111B is disposed above the reticle 20. In FIGS. 2 and 3, thearrows represent the directions in which gas flows. The gas flow path111A (in FIG. 2) comprises a wide area 112A, which is disposed below thereticle 20, and a narrow area 114A, which is not in line with thereticle 20. The gas flow path 111B (in FIG. 3) comprises a narrow area112B, which is disposed above the reticle 20, and a wide area 114B,which is not in line with the reticle 20. Here, Formula 1 is establishedfrom Bernoulli's theorem: $\begin{matrix}{{{\frac{1}{2}V_{1}^{2}} + \frac{P_{1}}{\rho} + {g\quad Z_{1}}} = {{\frac{1}{2}V_{2}^{2}} + \frac{P_{2}}{\rho} + {g\quad Z_{2}}}} & (1)\end{matrix}$

[0056] where ρ is the density of the gas flowing in the direction of thearrows shown in FIGS. 2 and 3, A₁ is the cross-sectional area of each ofthe areas 112A and 112B that is perpendicular to the plane of the sheet(FIGS. 2 and 3), P₁ is the pressure of the gas in each of the areas 112Aand 112B, V₁ is the speed of the gas, Z₁ is the height from a referencesurface at the center of each of the areas 112A and 112B, A₂ is thecross-sectional area of each of the areas 114A and 114B that isperpendicular to the plane of the sheet (FIGS. 2 and 3), P₂ is thepressure of the gas in the areas 114A and 114B, V₂ is the speed of thegas, and Z₁ is the height from a reference surface at the center of eachof the areas 114A and 114B. Here, since the centers of the areas 112Aand 112B and the corresponding areas 114A and 114B coincide, Z₁=Z₂.Therefore, Formula 1 becomes Formula 2. When Formula 2 is transformed,it becomes Formula 3. $\begin{matrix}{{{\frac{1}{2}V_{1}^{2}} + \frac{P_{1}}{\rho}} = {{\frac{1}{2}V_{2}^{2}} + \frac{P_{2}}{\rho}}} & (2)\end{matrix}$

 P ₁ −P ₂=0.5×ρ×(V ₂ ² −V ₁ ²)  (3)

Since V ₁ ×A ₁ =V ₂ ×A ₂  (4)

[0057] and $\begin{matrix}{{V_{2} = {\frac{A_{1}}{A_{2}}V_{1}}},} & (5)\end{matrix}$

[0058] Formula 6 is established:

P ₁ −P ₂=0.5·ρ·V ₁ ²·{(A ₁ /A ₂)²−1}  (6)

[0059] When the central lines of the areas 112A and 112B and thecorresponding areas 114A and 114B do not coincide, Formula 6 becomes:

P ₁ −P ₂=0.5×ρ×V ₁ ²×{(A ₁ /A ₂)²−1}+ρ×g×(Z ₂ −Z ₁).

[0060] However, when P₁−P₂ is on the order of 100 Pa, ρ×g×(Z₂−Z₁) is12.25×(Z₂−Z₁), so that when Z₂−Z₁ is equal to or less than a value onthe order of 0.1 (10 cm), Formula 6 produces an error on the order of10%, which is not a problem from a practical standpoint.

[0061] P₁−P₂ is a difference in pressure between the areas 112A and 112Band the corresponding areas 114A and 114B. When the gas flow paths 111Aand 111B are open to the atmosphere in order to set P₂ at atmosphericpressure, it is possible to apply the pressure difference obtained bythe above formula against the weight of the reticle 20 (that is, ingeneral, in the embodiment, G=3.17 and A_(R)=0.152² when G representsthe weight of the reticle and A_(R) is the area of projection of thereticle 20). By setting P₂ at atmospheric pressure and causing the spacearound the reticle 20 to be open, heat will not be confined in the areaaround the reticle 20 as it is in the first embodiment disclosed inJapanese Patent Laid-Open No. 10-214780, thereby making it possible toprevent deformation and distortion of the reticle 20 as a result ofrestricting a temperature rise in the reticle 20.

[0062] The relationship between P₁ (upstream gauge pressure) and V₁(upstream gas speed) is shown in FIG. 4. An area ratio which is greaterthan one means that the gas flow paths 111A and 111B have shrunk,whereas an area ratio less than one means that they have expanded.

[0063] In order to apply a pressure equivalent to the self-weight of thereticle 20 after rewriting Formula 4 using 140 Pa, which is equivalentto the self-weight of the reticle 20, when the gas flow path 111A iscontracted (that is, when A₁>A₂),

V ₁=15/{(A ₁ /A ₂)²−1}^(½)

[0064] On the other hand, when the gas flow path 111B is expanded (thatis, when A₁<A₂),

V ₁=15/{1−(A ₁ /A ₂)²}^(½)

[0065] Referring to FIGS. 2 and 4, when A₁/A₂=2 in the case in which thegas flow path 111A is disposed below the reticle 20, the required gasspeed is V₁=8.7 m/sec. Similarly, referring to FIGS. 3 and 4, whenA₁/A₂=0.5 in the case in which the gas flow path 111B is disposed abovethe reticle 20, the required gas speed is V₁=8.7 m/sec.

[0066] According to the correcting device 100, by blowing gas, such asair or nitrogen, to the gas flow paths having two continuously formedareas having different cross-sectional areas, a difference in pressurecan be produced between both of the areas as a result of making use ofBernoulli's theorem. By properly making use of the pressure difference,the correcting device 100 can correct distortion caused by factors otherthan the self-weight of the reticle 20. In addition, the correctingdevice 100 can restrict a temperature rise in the reticle 20, caused byheat of exposure light emitted from the illumination device 10, bycooling the reticle 20 as a result of blowing gas onto the reticle 20.

[0067] In FIG. 1, the gas pipe 110, which is recessed above the reticle20, is used. Therefore, in FIG. 1, the area 114 is provided not onlybehind the area 112 but also in front of the area 112 (that is, upstreamin terms of the gas that is being blown). Since the cross-sectional areaof the area 112 is smaller than the cross-sectional area of theupstream-side area 114, the temperature of the gas in the area 112 canbe reduced, so that the temperature rise in the reticle 20 caused by theexposure heat can be restricted.

[0068] In FIG. 1, the structure shown FIG. 3 can be used instead of thestructure shown in FIG. 2. More specifically, the gas pipe 110 isprovided opposite to the plate 40 in relation to the reticle 20. Ingeneral, a pellicle or a film (not shown) is provided at the plate 40side. The pellicle is a transparent protective film (or a structuralmember thereof) provided within a certain distance from the reticle 20in order to prevent foreign matter from adhering onto the reticle 20.Therefore, by providing the gas pipe 110 opposite to the plate 40 inrelation to the reticle 20, it is possible to prevent the reticle 20from deforming and breaking, when gas flows, by using the pellicle, sothat the reticle 20 can be indirectly protected.

[0069] The structures of the gas pipe 110 and the reticle 20 shown inFIG. 1 are merely examples. For example, as shown in FIGS. 5 and 6, acorrecting device 100C, including a gas pipe 110C defined by a gas flowpath 111C, having areas 112C and 114C, may be formed by a pair ofcross-sectionally parallel surfaces 116C and 118C in order to cause thereticle 20 to protrude from a bottom surface 118C (or a reticle table)of the gas pipe 110. Here, FIG. 5 is a perspective view of amodification of the correcting device shown in FIG. 1, and FIG. 6 is asectional view thereof. As shown in FIG. 7, the reticle 20 is secured toa reticle chuck 22 through a vacuum hole 23 formed at the reticle chuck22, which is accommodated in a rectangular hole 25 formed in the centerof a rectangular reticle stage 24. By properly setting a height H of thereticle stage 24, a cross-sectional area A₁ of the area 112C shown inFIG. 5 is determined. A cross-sectional area A₂ of the area 114C isdefined by the pair of parallel surfaces 116C and 118C of the gas pipe110C.

[0070] The blowing section 120 shown in FIG. 1 blows gas, whosetemperature is controlled at a certain temperature, towards the scanningdirection of the reticle stage 24. For example, as shown in FIG. 5, theblowing section 120 includes a filter 122 and a duct 124. For the gas,air may be used when the light source 12 is a mercury lamp, whilenitrogen or the like may be used when the light source 12 is a laser.The filter 122 is provided at the exit of the blowing section 120 andcleans the gas that blows from the blowing section 120. For the filter122, a HEPA (manufactured by Nippon Cambridge Filter Co., Ltd.) may beused. The duct 124 is connected to an external gas source (not shown) inorder to cause the gas to flow into the blowing section 120.

[0071] The gas pipe 110 shown in FIG. 1 includes a transmission window117, formed of a material such as glass that passes exposure light fromthe illumination optical system 14, at a top surface 116 thereof.

[0072] As shown in FIG. 6, it is preferable for the correcting device100 to further include a smoothing section 130, disposed between theareas 112C and 114C, which smooths the movement of the gas flowingtherebetween. The smoothing section 130 can prevent the gas fromdeviating from Bernoulli's theorem, which would be caused by the gasswirling between the areas 112C and 114C. Although in the embodiment thesmoothing section 130 is formed by a triangular column that is providedat the upstream side and the downstream side of the reticle stage 24, aninclined portion does not have to take the form of a straight line as inthe embodiment. It may take any form, such as a curved form or anarcuate form, as long as it can smooth the movement of the gas.

[0073]FIG. 8 illustrates a correcting device 100D, which is amodification of the correcting device shown in FIG. 1, in which, similarto the gas pipe 110 shown in FIG. 1, a gas pipe 110D, which is recessedabove the reticle 20, is formed at a top surface 116D. In themodification, due to the depth of the recess in the top surface 116D,the cross-sectional area of an area 112D can be adjusted. Accordingly,this modification has the feature that a height H of the reticle stage24 shown in FIG. 7 does not have to be set at so high a value.

[0074]FIGS. 9 and 10 illustrate a correcting device 100E, which is stillanother modification of the correcting device shown in FIG. 1. Morespecifically, a gas pipe 110E is formed so that the reticle stage 24 isaccommodated in a recess 119 formed in a bottom surface 118E (reticletable), and so that the top surface of the reticle stage 24 and the topsurface of the other portions of the bottom surface 118E are at the sameheight. A cross-sectional area Al of an area 112E and a cross-sectionalarea A₂ of an area 114E, both of which are illustrated in FIG. 9, aredefined by a stepped portion of a top surface 116E of the gas pipe 110.

[0075] The correcting device 100E further comprises a control section140, a memory 142, and a pressure sensor 150. The blowing section 120,the control section 140, the memory 142, and the pressure sensor 150form a (feedback) control system. In this modification, the controlsection 140 causes the difference in pressure between the front and backsurfaces of the reticle 20 to be detected through the pressure sensor150 in order to control the blowing section 120 (or a driver (not shown)of the blowing section 120) so that the pressure difference becomes apredetermined value (for example, so that it becomes a value required tocancel the deformation of the reticle 20 caused by its own weight due togravity, or, more specifically, so that it satisfies P₁−P₂=0.5·ρ·V₁²·{(A ₁/A₂)²−1}=−G/A_(R).Therefore, the correcting device 100E cancorrect the distortion of the reticle caused by its own weight.

[0076] The control section 140 is connected to the 1de pressure sensor150 in order to control, for example, the blast volume, and the gasspeed and the gas temperature at the blowing section 120 based on thedetection results of the pressure sensor 150. The control section 140 isalso connected to the memory 142, so that the memory 142 can store themethod of controlling the blowing section 120 carried out by the controlsection 140 and/or the data used for the method. The memory 142 may be aread-only memory (ROM), a random-access memory (RAM), other such storagedevices. In this modification, the control section 140 is a controlsection of the exposure apparatus 1. However, if necessary, this controlsection 140 may be a control section of an external device, theillumination device 10, and the projection optical system 30. Inaddition, separate control sections may be provided for these componentparts.

[0077] The pressure sensor 150 comprises a sensor 152, disposed at thefront side of the reticle 20 inside a gas flow path 111E, and a sensor154, disposed at the back side of the reticle 20 below a bottom surface118E of the gas pipe 110E. For the pressure sensor 150, sensors of anystructure known in the industrial field, such as a strain gauge, a loadcell, a piezoelectric device, a pressure electrically conductive sheet,a pressure sensitive polymer, a photodiode, an electrostatic capacitive(differential pressure) sensor, a Bourdon tube, a bellows, a diaphragm,or a torsion bar may be used. The structures and operations of thesetypes of sensors are well known, and will not be described in detailbelow.

[0078]FIG. 11 is an external perspective view of a correcting device100F, which is still another modification of the correcting device 100shown in FIG. 1. The correcting device 100F is similar to the correctingdevice 100E, but differs from it in that, unlike the area 114E thatspreads vertically with respect to the area 112E, an area 114F spreadstowards the left and right with respect to an area 112F. In other words,a top surface 116F of a gas flow path 110F (not shown) is maintainedhorizontally with respect to the areas 112F and 114F. By combining thestructures shown in FIGS. 9 and 11, the area 114F may spread in theupward and downward directions and towards the left and right withrespect to the area 112F.

[0079] In the present invention, it does not matter what scanning methodis used on the reticle 20, so that, for example, as shown in FIGS. 12 to15, the present invention may be applied to a scanning exposureapparatus 200. Referring to FIGS. 12 and 13, the correcting device 100Fis used with the reticle 20 that is scanned in synchronism by a pair oflinear motors 204 and 227, which can move perpendicular to each other.FIG. 13 shows a state in which the reticle 20 has moved towards the leftfrom its position shown in FIG. 12.

[0080] Hereafter, with reference to FIGS. 14 and 15, the exposureapparatus 200 will be described. FIG. 14 is a schematic side view of theexposure apparatus 200, and FIG. 15 is an external perspective view ofthe exposure apparatus 200. Through a projection optical system 202, theexposure apparatus 200 projects a portion of the circuit pattern of thereticle 20 disposed on a reticle stage 201, which holds the reticle 20and which can be used for performing a scanning operation in the Ydirection, onto a wafer W disposed on an XY stage 203. The exposureapparatus 200 is a step-and-scan exposure apparatus which is used toproject the pattern of the reticle 20 onto the wafer W by exposure as aresult of scanning the reticle 20 and the wafer W in the Y direction insynchronism with each other with respect to the projection opticalsystem 202 and which interposes stepwise movements in order to applyscanning exposure light to a plurality of shots on the wafer W.

[0081] The reticle stage 201 is driven in the Y direction by the linearmotors 204 and 227. An X stage 203 a of the wafer stage 203 isconstructed so that it is driven in the X direction by a linear motor205, and a Y stage 203 b is constructed so that it is driven in the Ydirection by a linear motor 206. The synchronized scanning operation ofthe reticle 20 and the wafer W is carried out by driving the reticlestage 201 and the Y stage 203 b in the Y direction at a fixed speedratio (for example, 4:1, where the sign means opposite direction) whilelaser interferometers 222 and 223 monitor the locations of the reticlestage 201 and the Y stage 203 b in the Y direction. The wafer W is movedstepwise in the X direction by the X stage 203 a.

[0082] The wafer stage 203 is provided on a stage table 207, which issupported on, for example, the floor at three points through threedampers 208. The reticle stage 201 and the projection optical system 202are provided on a telescopic surface plate 209, which is supportedthrough three dampers 211 and column supports 212 on a base frame 210disposed on, for example, the floor. Although the dampers 203 are activedampers that actively deaden or isolate vibration in six axialdirections, they may be passive dampers. In addition, dampers do notneed to be used to support the telescopic surface plate 209.

[0083] At three points between the telescopic surface plate 209 and thestage table 207, the exposure apparatus 200 includes distance-measuringmeans, such as measurement laser interferometers or microcomputers.Light projecting means 221 and light-receiving means 222 form a focussensor for detecting whether or not the wafer W on the wafer stage 203is positioned at a focal plane of the projection optical system 202.More specifically, the light-projecting means 221, secured to thetelescopic surface plate 209, projects light onto the wafer W from anoblique direction, and the light-receiving means 222 detects thelocation of the reflected light in order to detect the location of thesurface of the wafer W in the optical axis direction of the projectionoptical system 202.

[0084] In the structure, transporting means (not shown) transports thewafer W onto the wafer stage 203 via a transportation path between thetwo column supports 212 at the front portion of the exposure apparatus200. When a predetermined alignment is completed, the exposure apparatus200 transfers the pattern of the reticle 20 onto a plurality of exposureareas of the wafer W by exposure while it repeats scanning exposureoperations and causes stepwise movements to be repeated. In the scanningexposure operation, the reticle stage 201 and the Y stage 203 b aremoved at a predetermined speed ratio in the Y direction (scanningdirection). Using slit-shaped exposure light, the pattern on the reticle20 is scanned, and the wafer W is scanned using the projection image ofthe pattern in order to project the pattern of the reticle 20 onto apredetermined exposure area of the wafer W by exposure. During thescanning exposure operation, the height of the surface of the wafer W ismeasured by the focus sensor. Based on the measured value, the heightand tilt of the wafer stage 203 are controlled in real time in order tocorrect the focus. After completion of a scanning exposure operation onone exposure area, by driving the X stage 203 a in the X direction inorder to move the wafer W stepwise, another exposure area is positionedat a scanning exposure starting location and is, then, subjected toscanning exposure. By combining the stepwise movements in the Xdirection and the movements for performing scanning exposure in the Ydirection, in order to allow the exposure operations to be successivelyperformed efficiently with respect to the plurality of exposure areas onthe wafer W, the location of each of the exposure areas, scanning in the+Y or −Y direction, the order in which each exposure area is exposed,and the like, are set.

[0085] In the exposure apparatus 200 shown in FIG. 14, light that hasbeen emitted from a laser interferometer light source (not shown) iscaused to enter the Y-direction laser interferometer 224. The light thathas entered the Y-direction laser interferometer 224 is divided by abeam splitter (not shown) inside the laser interferometer 224 into lightthat is directed towards a fixed mirror (not shown) disposed inside thelaser interferometer 224 and light that is directed towards aY-direction moving mirror (not shown). The light that is directedtowards the Y-direction moving mirror passes through a Y-directionlength measurement optical path (not shown), and, then, impinges uponthe Y-direction moving mirror secured to the reticle stage 201. Here,the light that is reflected passes again through the Y-direction lengthmeasurement optical path, returns to the beam splitter inside the laserinterferometer 202, and is superimposed on the light reflected at thefixed mirror. At this time, by detecting changes in the interference oflight, the distance of movement in the Y direction is measured. Theinformation regarding the distance of movement measured in this way isfed back to a scanning control device (not shown), which controls thepositioning operation of a scanning location of the reticle stage 201.

[0086] The reticle 20 is deformed as a result of being heated by theexposure light from the illumination device 10. In the presentinvention, it is possible to correct both thermal deformation of thereticle 20 and flexure of the reticle 20 caused by its own weight.Hereafter, an example of correcting the deformations of the reticle 20will be given with reference to FIG. 16. FIG. 16 is a schematic blockdiagram of a detecting section 150 that detects any distortion of thereticle 20. The reticle 20 is secured to the reticle chuck 22 through asuction pad 21. The reticle 20 is distorted by a flexure amount δ causedby its own weight, heat, and other factors. The detecting section 150comprises a light-emitting section 152, lenses 154 and 156, and alight-receiving section 158. In this example, the light-emitting section152 and the light-receiving section 158 form a light-reflectivephoto-interrupter. A light-emitting diode (LED), a laser diode (LA), orthe like may be used for the light-emitting section 152. A photodiode,phototransistor, a photo IC, or the like may be used for thelight-receiving section 158. The light-emitting section 152 illuminatesa pattern formed on the surface of the reticle 20. Light reflectedtherefrom is detected by the light-receiving section 158 in order todetect the flexure amount δ of the reticle 20. The detection resultsprovided by the light-receiving section 158 is transmitted to, forexample, the control section 140 shown in FIG. 10. The control section140 makes use of such results to control the blowing section 120. Thecontrol section 140 controls feedback of the blowing section 120 so thatthe flexure amount δ of the reticle 20 becomes zero in order to correctthe distortions of the reticle 20.

[0087] In the exposure, light beams emitted from the light source 12 areused to subject the recticle 20 to, for example, Koehler illumination bythe illumination optical system 14. Since the exposure apparatus 1 makesit possible to reduce or remove the distortions of the reticle 20, thepattern of the reticle 20 can be transferred onto the resist with highprecision, so that a high-quality device (such as a semiconductordevice, a liquid crystal display (LCD) device, an image pickup device(including a charge-coupled device (CCD)), and a thin-film magnetichead) can be provided.

[0088] Referring to FIGS. 17 and 18, an embodiment of a deviceproduction method using the above-described exposure apparatus 1 will bedescribed. FIG. 17 is a flowchart used to illustrate the production of adevice (such as a semiconductor chip of, for example, an integratedcircuit (IC) or a large-scale integrated circuit (LSI), an LCD, and aCCD). Here, an example of producing a semiconductor chip will bedescribed. In Step 1, a circuit pattern is designed for the device. InStep 2, a mask having the designed circuit pattern formed thereon isproduced. In Step 3, a wafer is produced, using silicon or othermaterials. In Step 4 (wafer process or pre-processing step), the maskand the wafer are used to actually form the circuit on the wafer usinglithography techniques. Then, in the following step, Step 5,(post-processing step), the wafer produced in Step 4 is formed into asemiconductor chip, wherein assembly (dicing, bonding), packaging (ofthe chip), and the like are performed. In Step 6, the semiconductordevice produced in Step 5 is inspected by conducting operationconfirmation tests, durability tests, and the like. Thereafter, in Step7, the finished semiconductor device is shipped.

[0089]FIG. 18 is a detailed flowchart of Step 4 (the wafer process). InStep 11, the surface of the wafer is oxidized. Then, in Step 12(chemical-vapor deposition (CVD) step), an insulation film is formed onthe wafer surface. In Step 13, an electrode is formed on the wafer by,for example, evaporation. In Step 14, ions are implanted into the wafer.In Step 15, a photosensitization agent is coated onto the wafer. In Step16, the mask circuit pattern is printed onto the wafer by exposure usingthe exposure apparatus 1. In Step 17, the exposed portion of the waferis developed. In Step 18, portions other than where the developed resistimage is formed are etched. In Step 19, unwanted resist is removed fromthe wafer after etching. Multiple circuit patterns are formed on thewafer by repeating the above-described steps. By virtue of thisembodiment of the device production method, devices having a higherquality than conventional devices can be produced.

[0090] Except as otherwise discussed herein, the various componentsshown in outline or in block form in the Figures are individually wellknown and their internal construction and operation are not criticaleither to the making or using or to a description of the best mode ofthe invention.

[0091] While the present invention has been described with reference towhat are presently considered to be the preferred embodiments, it is tobe understood that the invention is not limited to the disclosedembodiments. On the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass all suchmodifications and equivalent structures and functions.

What is claimed is:
 1. A correcting device comprising: a gas flow pathincluding a first area and a second area, the first area being formedabove a reticle having formed thereon a pattern that is projected onto amaterial to be processed in order to form an image of the pattern on thematerial to be processed, and the second area being connected to thefirst area, having a cross-sectional area that is different from that ofthe first area, and not being disposed in line with the reticle; and ablowing section that blows gas to the gas flow path.
 2. A correctingdevice according to claim 1, wherein the second area is locateddownstream from the first area in terms of the gas flow of the gas flowpath, and the cross-sectional area of the first area is smaller than thecross-sectional area of the second area.
 3. A correcting deviceaccording to claim 2, wherein said gas flow path includes a third areaprovided upstream from the first area in terms of the gas flow of thegas flow path, and the cross-sectional area of the third area is greaterthan the cross-sectional area of the first area.
 4. A correcting deviceaccording to claim 1, further comprising a smoothing section, disposedbetween the first and second areas, for smoothing movement of the gasbetween the first and second areas.
 5. A correcting device according toclaim 1, wherein the gas flow path is disposed opposite to the materialto be processed, in terms of the reticle.
 6. A correcting deviceaccording to claim 1, further comprising a control section that controlsthe blowing section so that, when the density of the gas is ρ, theweight of the reticle is G, the area of projection of the reticle isA_(R), the cross sectional area of the first area is A₁, the pressure ofthe gas in the first area is P₁, the velocity is V₁, the cross-sectionalarea of the second area is A₂, and the pressure of the gas in the secondarea is P₂, the following formula is satisfied: P ₁ −P ₂=0.5·ρ·V ₁ ²·{(A₁ /A ₂)²−1}=−G/A _(R).
 7. A correcting device according to claim 6,wherein said control section controls the speed of the gas blown by saidblowing section.
 8. A correcting device according to claim 6, wherein P₂is atmospheric pressure.
 9. A correcting device according to claim 6,wherein said control section controls the temperature of the gas flownby said blowing section.
 10. A correcting device comprising: a blowingsection that blows gas onto a reticle having formed thereon a pattern tobe projected onto a material to be processed; a detecting section thatdetects pressure at front and back surfaces of the reticle and producesa detection result; and a control section that receives the detectionresult and controls the blowing section so that a difference between thepressure is maintained to be a predetermined value, after receiving thedetection result provided by the detecting section.
 11. A correctingdevice according to claim 10, wherein said control section controls thespeed of the gas blown by said blowing section.
 12. A correcting deviceaccording to claim 10, wherein the predetermined amount is determined inaccordance with the self-weight of the reticle.
 13. A correcting deviceaccording to claim 10, wherein said control section controls thetemperature of the gas blown by said blowing section.
 14. A correctingdevice comprising: a blowing section that blows gas onto a reticlehaving formed thereon a pattern to be projected onto a material to beprocessed; a detecting section that detects a flexure amount of thereticle and produces a detection result; and a control section thatreceives the detection result and controls the blowing section so thatthe flexure amount is maintained to be zero, after receiving thedetection result provided by said detecting section.
 15. A correctingdevice according to claim 14, wherein said control section controls thespeed of the gas blown by said blowing section.
 16. A correcting deviceaccording to claim 14, wherein said control section controls thetemperature of the gas blown by the blowing section.
 17. A method ofproducing a device, comprising the steps of: blowing gas to a gas flowpath including a first area and a second area, the first area beingformed above a reticle having formed thereon a pattern that is projectedonto a material to be processed in order to form an image of the patternon the material to be processed, and the second area being connected tothe first area, having a cross-sectional area that is different fromthat of the first area, and not being disposed in line with the reticle;subjecting the material to be processed to a projection exposureoperation using the reticle; and performing a predetermined processingoperation on the material that has been subjected to the projectionexposure operation to produce a device.
 18. A method of producing adevice according to claim 17, further comprising detecting distortion ofthe reticle and controlling the step of blowing gas so that distortionof the reticle is reduced based on the detection of the distortion ofthe reticle.
 19. A device comprising: a chip formed by dicing thematerial processed by the production method of claim 17; and a packagefor the chip.
 20. A device comprising: a chip formed by dicing thematerial processed by the production method of claim 18; and a packagefor the chip.
 21. An exposure apparatus comprising: a gas flow pathincluding a first area and a second area, the first area being formedabove a reticle having formed thereon a pattern that is projected onto amaterial to be processed in order to form an image of the pattern on thematerial to be processed, and the second area being connected to thefirst area, having a cross-sectional area that is different from that ofthe first area, and not being disposed in line with the reticle; ablowing section that blows gas to the gas flow path; an illuminationoptical system that illuminates the pattern; and a projection opticalsystem that projects the pattern onto the material to be processed inorder to form an image of the pattern on the material to be processed.22. An exposure apparatus according to claim 21, wherein the second areais located downstream from the first area in terms of the gas flow ofthe gas flow path, and the cross-sectional area of the first area issmaller than the cross-sectional area of the second area.
 23. Anexposure apparatus according to claim 22, wherein said gas flow pathincludes a third area provided upstream from the first area in terms ofthe gas flow of the gas flow path, and the cross-sectional area of thethird area is greater than the cross-sectional area of the first area.24. An exposure apparatus according to claim 21, further comprising asmoothing section, disposed between the first and second areas, forsmoothing movement of the gas between the first and second areas.
 25. Anexposure apparatus according to claim 21, wherein the gas flow path isdisposed opposite to the material to be processed, in terms of thereticle.
 26. An exposure apparatus according to claim 21, furthercomprising a control section that controls the blowing section so that,when the density of the gas is ρ, the weight of the reticle is G, thearea of projection of the reticle is A_(R), the cross sectional area ofthe first area is A₁ the pressure of the gas in the first area is P₁,the velocity is V₁, the cross-sectional area of the second area is A₂,and the pressure of the gas in the second area is P₂, the followingformula is satisfied: P ₁ −P ₂=0.5·ρ·V ₁ ²·{(A ₁ /A ₂)²−1}=−G/A _(R).27. A correcting device according to claim 26, wherein said controlsection controls the speed of the gas blown by said blowing section. 28.A correcting device according to claim 26, wherein P₂ is atmosphericpressure.
 29. A correcting device according to claim 26, wherein saidcontrol section controls the temperature of the gas blown by saidblowing section.
 30. An exposure apparatus comprising: a blowing sectionthat blows gas onto a reticle having formed thereon a pattern to beprojected onto a material to be processed; a detecting section thatdetects pressure at front and back surfaces of the reticle and producesa detection result; a control section that receives the detection resultand controls the blowing section so that a difference between thepressures is maintained to be a predetermined value, after receiving thedetection result provided by the detection section; an illuminationoptical system that illuminates the pattern; and a projection opticalsystem that projects the pattern onto the material to be processed inorder to form an image of the pattern on the material to be processed.31. A correcting device according to claim 30, wherein said controlsection controls the speed of the gas blown by said blowing section. 32.An exposure apparatus according to claim 30, wherein the predeterminedamount is determined in accordance with the self-weight of the reticle.33. A correcting device according to claim 30, wherein said controlsection controls the temperature of the gas blown by said blowingsection.
 34. A correcting device comprising: a blowing section thatblows gas onto a reticle having formed thereon a pattern to be projectedonto a material to be processed; a detecting section that detects aflexure amount of the reticle and produces a detection result; a controlsection that receives the detection result and controls the blowingsection so that the flexure amount is maintained to be zero, afterreceiving the detection result provided by said detecting section; anillumination optical system that illuminates the pattern; and aprojection optical system that projects the pattern onto the material tobe processed in order to form an image of the pattern on the material tobe processed.
 35. An exposure apparatus according to claim 34, whereinsaid control section controls the speed of the gas blown by said blowingsection.
 36. An exposure apparatus according to claim 34, wherein saidcontrol section controls the temperature of the gas blown by saidblowing section.